1. Field of the Invention
This invention relates to particular modified zeolite catalysts and their uses in the selective production of para-dialkylsubstituted benzenes and to a process for converting certain charge stocks to a high yield of para-dialkylsubstituted benzenes.
2. Description of the Prior Art
U.S. Pat. No. 2,904,607 refers to the alkylation of aromatic hydrocarbons with an olefin in the presence of a crystalline metallic aluminosilicate having uniform pore openings of about 6 to 15 Angstrom units. U.S. Pat. No. 3,251,897 describes alkylation of aromatic hydrocarbons in the presence of X- or Y-type crystalline aluminosilicate zeolites, specifically such type zeolites wherein the cation is rare earth and/or hydrogen. U.S. Pat. Nos. 3,751,504 and 3,751,506 describes vapor phase alkylation of aromatic hydrocarbons with olefins, e.g. benzene with ethylene, in the presence of a ZSM-5 type zeolite catalyst.
More recently, U.S. Pat. No. 4,090,981 has disclosed a catalyst particularly applicable for the selective production of para-dialkylsubstituted benzenes. It comprises a porous crystalline aluminosilicate zeolite having silica deposited on the surface thereof. U.S. Pat. No. 4,127,616 is directed to the process utilizing these zeolite compositions.
U.S. Pat. No. 3,962,364 describes the alkylation of aromatic compounds such as benzene and toluene with olefinic hydrocarbons, such as ethylene, utilizing zeolites (ZSM-5, ZSM-11, ZSM-35, etc.) which have been reacted with phosphorous compounds.